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This week we looked at GPS which stands for Global Positioning System. The idea behind GPS is based on time and the position of a network of satellites. The satellites have very accurate clocks and the satellite locations are known with great precision.

Each GPS satellite continuously transmits a radio signal containing the current time and data about its position. The time delay between when the satellite transmits a signal and the receiver receives it is proportional to the distance from the satellite to the receiver. A GPS receiver monitors multiple satellites and uses their locations and the time it takes for the signals to reach it to determine its location . At a minimum, four satellites must be in view of the receiver for it to get a location fix.

We used the Adafruit Ultimate GPS Breakout connected to an Arduino as our GPS receiver. It’s very easy to set up, all we did was install the Adafruit GPS library on our Arduino and this gave us a load of programmes to chose from. We used the parsing sketch which gave us Longitude, Latitude and our location in degrees which we used with google maps to show our location.

This will save a picture called foo in the folder you ran your script from.

OpenCV (Open source computer vision) is a library of programming functions mainly aimed at real-time computer vision. We tried a couple of scripts out, one from the Hackers group, thanks Kevin, that detects colours and another one that detects shapes, we will be looking at this much more in the next few sessions but next Saturday we will look at using an Arduino and a Raspberry Pi together.

I was away this week so Dave led the group, they did a couple of Arduino projects. They revisited the traffic lights from December but this time used the Arduino to control them and then moved on to a temperature and humidity sensor called the DHT11.

Here is the wiring diagram for the traffic lights and you can find the code here.

Here is the wiring diagram for the DHT11 and the code is also on Dropbox here.

We will be doing more with the Arduino particularly for some of our projects.

This week we continued working on our Astro Pi entries and we also looked at FreeCAD and Fritzing which are tools that will help us with building our projects.

FreeCAD, available for download from here, is used for 3D modelling and allows us design very complicated things from simple 3D shapes such as cubes and cylinders. Here are a couple of quick videos to get you started.

Then we looked at Fritzing, download from here, an application for drawing very easy to understand circuits, here’s how to draw a simple circuit using it.

Dave will be leading next Saturday’s session and I will see you again on the ninth of Feb.

This week we started getting our entries ready for the Astro Pi Mission Zero Challenge by looking at whose aboard the International Space Station now and what they’re doing. We followed this up by taking another look at programming the Trinket Astro Pi emulator.

We also had a small brainstorming session to come up with ideas for projects that we will be working on for the rest of the year.

This week we started looking at physical computing and the Raspberry Pi. This involves attaching various components such as sensors, motors or controllers to the GPIO pins on our Pi. This week we connected a LED and two buttons, and we used the GPIO Zero module for Python to control them. I’ve made a video, it’s a little bit long, that covers everything from Saturday’s session.

At the end of the session the group started working on a traffic light idea and we will combine this with HC-SR04 ultrasonic distance sensor next week to create a measuring device.